This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the disclosed methodologies and techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Hydrocarbon reserves are becoming increasingly difficult to locate and access, as the demand for energy grows globally. Typically, various components are utilized to collect measurement data and then to predict the location of potential hydrocarbon accumulations. The modeling may include factors, such as (1) the generation and expulsion of liquid and/or gaseous hydrocarbons from a source rock, (2) migration of hydrocarbons to an accumulation in a reservoir rock, (3) a trap and a seal to prevent significant leakage of hydrocarbons from the reservoir.
At present, reflection seismic is the dominant technology for the identification of hydrocarbon accumulations. This technique has been successful in identifying structures that may host hydrocarbon accumulations, and may also be utilized to image the hydrocarbon fluids within subsurface accumulations as direct hydrocarbon indicators (DHIs). However, seismic imaging of geological occurrences may be challenging in several cases where acoustic impedance contrasts that generate DHIs are greatly diminished or absent (e.g. imaging of subsurface geological occurrences at increasing depth, sub-volcanic, or sub-salt). Consequently, this technology may lack the required fidelity to provide accurate assessments of the location, volume, and fluid composition of subsurface hydrocarbon accumulations due to poor imaging of the subsurface.
Current non-seismic hydrocarbon detection technologies, such as potential field based methods like gravity or magnetics, provide coarse geologic subsurface control by sensing different physical properties of rocks, but lack the fidelity to identify hydrocarbon accumulations. Other non-seismic hydrocarbon accumulation detection technologies may include geological extrapolations of structural or stratigraphic trends that lead to exploration prospects, but cannot directly detect hydrocarbon accumulation materiality.
Hydrocarbon seepage at the sea floor or on land provides some indication of an active or working hydrocarbon system where hydrocarbons have been generated and expulsed during the thermal maturation of a source rock at depth, and have migrated via more or less complex migration pathways to the surface. Alternatively, it may be associated with migration of hydrocarbons produced during the microbial degradation of organic matter in the subsurface that may or may not be associated with an accumulation. However, it is not possible using current technologies to determine whether such hydrocarbon seepages migrated directly from a source rock, from a failed trap without significant residence time within an accumulation, or from an existing hydrocarbon accumulation.
Further, the presence of non-hydrocarbon gases associated with hydrocarbon accumulations has implications for production and the economics of the accumulated hydrocarbons. Such non-hydrocarbon gases may include carbon dioxide, nitrogen, and hydrogen sulfide that were co-generated with the trapped hydrocarbons or were transported separately to the site of accumulation. There are no current direct pre-drill methods available to allow for the de-risking of non-hydrocarbon gases.
Many recent failures in hydrocarbon exploration have been associated with the inability to fully evaluate, understand, and appropriately risk the hydrocarbon system components, from source to seeps (migration, accumulation and leakage). Indeed, certain conventional technologies involve the identification and characterization of thermogenic hydrocarbons from seeps. However, there are no known tools that can directly link the geochemical composition of thermogenic hydrocarbon and/or biological species recovered from surface seeps to the size, depth, and fluid types/quality of subsurface hydrocarbon accumulations. A major advance in the ability to detect the presence, size, depth, and fluid type/quality of subsurface hydrocarbon accumulations would significantly improve hydrocarbon (HC) resource exploration in frontier and play extension settings. A method integrating existing and new biological and geochemical indicators is able to achieve this change, and integration with geological/geophysical contextual knowledge would further allow a breakthrough in opportunity identification. This invention provides a valuable, inexpensive, and rapid tool that can be used in hydrocarbon exploration at all business stage levels, from frontier exploration or extension of proven plays to high-grading prospects within proven plays.
As a result, geoscientists need to enhance techniques used for the identification of hydrocarbon accumulations. In particular, a need exists for pre-drill technologies capable of estimating the volume of subsurface hydrocarbon accumulations and technologies capable of determining the location, type (e.g. oil vs. gas) and quality (e.g. density) of the subsurface hydrocarbon accumulation.